Considerable uncertainty exists about the potential harm that shift work during pregnancy may impose on a mom's child, yet working night shifts during pregnancy is currently an established reality in the US. We have previously linked work schedules, particularly those involving night shifts, with an increased risk of spontaneous abortion and delivering pre-tem in the Nurses' Health Study 2 (NHS2). Now, we propose to continue our work by examining how exposure of the embryo and fetus to shift work may affect their health and chronic disease risk later in life. We will make use of a worldwide unique resource, which provides critical information on both moms and their offspring, including occupational shift work exposure during pregnancy: using existing data from the ongoing NHS2 cohort and Growing Up Today Study (GUTS), i.e. children of the nurses participating in NHS2, we will investigate the following 3 major hypotheses: (1) can shift work (prior to conception as well as during pregnancy) induce growth perturbations and altered mental health in the offspring, and how may this influence disease risk across the lifespan? (2) are worsened sleep parameters including lower overnight production of melatonin and higher awakening cortisol in young adulthood associated with such early life exposures? and (3) can we define critical developmental windows (e.g., preconception, embryonic, and fetal periods) during which shift work may influence chronic disease etiology. We have complete lifetime shift work history of the NHS2 moms of all 27,795 children in GUTS, 3,740 children whose moms additionally provided shift work history during pregnancy. In alignment with Healthy People 2020, this proposal addresses all NORA Sector Programs as well as the cross- sector programs Work Organization and Stress Related Disorders, and Cancer, Reproductive and Cardiovascular Diseases. Specifically, our proposal strives to explore whether night shifts may expose offspring of workers to heightened risk for disorders. Expected immediate outputs of our proposed research are publications, presentations/posters. Intermediate outcomes will be tracked by showing new policies that cite our work. We will disseminate our findings to other scientists through the peer-reviewed literature and scientific conferences. However, our primary target audience is workers - hence, we will communicate to nurses by our Nurses' Health Study 2 staff, as well as to other workers through the staff at NIOSH, using websites, newsletters, and social media presence. Our proposed research exemplifies the translation of research into practice (r2P) in that it may lead to actual changes in work practice for pregnant women. Ultimately, this is a potentially highly effective prevention practice, which can readily be adopte by any other workplace.